A chronic cough is more than just an annoyance. A chronic cough can ruin your sleep and leave you feeling exhausted. Severe cases of chronic cough can result in vomiting, lightheadedness, depression, even rib fractures.

Chronic cough is defined as lasting eight weeks or longer in adults, four weeks in children.

While it can sometimes be difficult to pinpoint the problem that's triggering a chronic cough, the most common causes are tobacco use, postnasal drip, asthma and acid reflux — the backflow of stomach acid that can irritate your throat. Chronic cough typically disappears once the underlying problem is treated.

A chronic cough can occur with other signs and symptoms, which may include:

A runny or stuffy nose

A feeling of liquid running down the back of your throat

Frequent throat clearing and sore throat

Hoarseness

Wheezing and shortness of breath

Heartburn or a sour taste in your mouth

In rare cases, coughing up blood

When to see a doctor

See your doctor if you have a cough that lingers for weeks, especially one that brings up sputum or blood, disturbs your sleep or affects your work.

An occasional cough is normal — it helps clear foreign substances and secretions from your lungs and prevents infection. But a cough that persists for weeks is usually the result of an underlying problem. In many cases, more than one cause is involved.

Major causes

Postnasal drip. When your nose or sinuses produce extra mucus, it can drip down the back of your throat and trigger your cough reflex. This condition is also called upper airway cough syndrome.

Asthma. An asthma-related cough may come and go with the seasons, appear after an upper respiratory tract infection, or become worse when you're exposed to cold air or certain chemicals or fragrances. In one type of asthma (cough-variant asthma), a cough is the main symptom.

Gastroesophageal reflux disease (GERD). In this common condition, stomach acid flows back into the tube that connects your stomach and throat (esophagus). The constant irritation can lead to chronic coughing. The coughing, in turn, worsens GERD — a vicious cycle.

Studies have shown that the above three causes, alone or in combination, are responsible for 90 percent of cases of chronic coughs.

Other causes

Infections. A cough can linger long after most symptoms of a cold, influenza, pneumonia or other infection of the upper respiratory tract have gone away. A not uncommon cause of a chronic cough in adults is pertussis, also known as whooping cough.

Blood pressure drugs. Angiotensin-converting enzyme (ACE) inhibitors, which are commonly prescribed for high blood pressure and heart failure, are known to cause chronic cough in some people.

Chronic bronchitis. This long-standing inflammation of your major airways (bronchial tubes) can cause congestion, breathlessness, wheezing and a cough that brings up discolored sputum. Most people with chronic bronchitis are current or former smokers.

Less common

Aspiration

Bronchiectasis

Bronchiolitis

Chronic bronchitis from an infectious disease

COPD

Cystic fibrosis

Foreign body aspiration — children

Laryngopharyngeal reflux

Lung cancer

Nonasthmatic eosinophilic bronchitis

Sarcoidosis

Being a current or former smoker is one of the leading risk factors for chronic cough. Frequent exposure to secondhand smoke also can lead to coughing and lung damage.

Women tend to have more-sensitive cough reflexes, so they're more likely to develop a chronic cough than are men.

Having a persistent cough can be exhausting. Coughing attacks can disrupt your sleep and cause a variety of other problems, including:

Headache

Dizziness

Excessive sweating

Urinary incontinence

Fractured ribs

While you may initially consult your family physician, he or she may refer you to a doctor who specializes in lung disorders (pulmonologist).

What you can do

It's a good idea to write a list that includes:

Detailed descriptions of your symptoms

Information about medical problems you've had

Information about the medical problems of your parents or siblings

All the medications and dietary supplements you take, including over-the-counter drugs

Questions you want to ask the doctor

What to expect from your doctor

A thorough medical history and physical exam can provide important clues about a chronic cough. Your doctor may ask some of the following questions:

When did your symptoms begin?

Do you now or have you ever smoked tobacco?

Does anyone in your family or workplace smoke?

Do you have heartburn?

Do you cough up anything? If so, what does it look like?

Do you take blood pressure medicine? If so, what type do you take?

When does your cough occur? After meals? At night?

Does anything relieve your cough?

Do you get more short of breath with exertion? Or on exposure to cold air?

What is your travel history?

Your medical history and physical examination help determine which tests your doctor will order. The goal of testing is to identify the underlying cause of your chronic cough.

Rather than testing, many doctors will try treating you for one of the common causes of chronic cough. Only if the treatments aren't successful will they begin testing for more unusual causes.

Imaging tests

X-rays. Although a routine chest X-ray won't reveal the most common reasons for a cough — postnasal drip, acid reflux or asthma — it may be used to check for lung cancer and pneumonia and other lung diseases. An X-ray of your sinuses may reveal evidence of a sinus infection.

Computerized tomography (CT) scans. CT scans also may be used to check your sinus cavities for pockets of infection.

Lung function tests

These simple, noninvasive tests measure how much air your lungs can hold and how fast you can exhale. This test is required to diagnose asthma. Sometimes you may also have an asthma challenge test, which checks how well you can breathe before and after inhaling a drug called methacholine (Provocholine).

Lab tests

If the mucus that you cough up is discolored, your doctor may want to test a sample of it for bacteria.

Scope tests

If your doctor isn't able to find an explanation for your cough, special scope tests may be considered to look for rare causes. These tests use a thin, flexible tube equipped with a light and camera to visualize structures within your body. This equipment can be inserted into your windpipe (trachea) and bronchi to look for abnormalities, as well as biopsy the inside lining of your airway (mucosa) to look for any cellular abnormalities.

Children

A chest X-ray and a spirometry test, at a minimum, are recommended to evaluate the cause of a chronic cough in a child.

Determining the cause of chronic cough is crucial to effective treatment. In many cases, more than one underlying condition may be causing your chronic cough.

If you're taking an angiotensin-converting enzyme (ACE) inhibitor medication, switch to an angiotensin-receptor blocker, which doesn't have a cough as a side effect.

Medications used to treat chronic cough may include:

Antihistamines and decongestants. These drugs are standard treatment for allergies and postnasal drip.

Inhaled asthma drugs. The most effective treatments for asthma-related cough are inhaled medications that reduce inflammation and widen your airways.

Antibiotics. If a bacterial infection is causing your chronic cough, antibiotics will be prescribed.

Acid blockers. When lifestyle changes don't take care of acid reflux, you may be treated with medications that block acid production. Some people need surgery to resolve the problem.

Cough suppressants. If the reason for your cough can't be determined, your doctor may prescribe a cough suppressant, especially if your cough is interfering with your sleep. However, there's no evidence showing they are effective. They should not be used in children because they may be harmful. A teaspoon (5 grams) of honey in warm water is a good home remedy to loosen up sputum (though it shouldn't be used in children younger than age 1).

A cautious approach on medications is recommended for children, as medications are generally not effective in relieving a nonspecific cough in children.

In many cases, there are measures you can take at home to help ease your chronic cough. Examples include:

Avoid allergens. If your chronic cough can be traced back to nasal allergies, try to avoid the substances that cause your symptoms.

Quit smoking. The most common cause of chronic bronchitis, smoking irritates your lungs and can worsen coughs caused by other factors.

Reduce acid reflux. A cough caused by acid reflux can often be treated with lifestyle changes alone. This includes eating smaller, more frequent meals; waiting three to four hours after a meal before lying down; and elevating the head of the bed at night.

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